PoAP is a feature that enables a new switch to auto-configure itself on boot-up on a network without the need for explicit configuration by the network administrator. In general, all that is required is that a Dynamic Host Configuration Protocol (“DHCP”) server and a Trivial File Transfer Protocol (“TFTP”) server be reachable from the new switch that is coming up. In short, the new switch transmits a DHCP request to obtain an IP address that it will use for the subsequent PoAP process. As part of the DHCP response, the new switch also receives information about the IP address of the TFTP server to contact, the boot image to be downloaded to the switch, the startup configuration to be applied to the switch (usually a template), as well as other necessary information. DHCP options such as 66 and 67, for example, are employed for obtaining this information from the DHCP server. PoAP operates on both management and in-band interfaces. The DHCP discover messages from the switch are sent out on all active interfaces. From the received DHCP offers, the switch selects one offer at random for which the DHCP request is sent. The switch then configures the acquired IP address on the selected interface/SVI 1 to continue with the PoAP process.
After the PoAP process completes, the IP address obtained from the DHCP server is released, the switch reboots with the downloaded boot image, and the switch goes about applying the downloaded startup configuration using, for example, Python/Tcl scripting. PoAP, as described above, is supported for a regular layer 2 network. For obvious reasons, PoAP would be beneficial in MSDC environments; however, for a variety of reasons, the method of PoAP described cannot be directly implemented for a new node joining an existing FP/TRILL cluster in MSDC environments.